Description

Opuntia robusta is a large vigourous prickly pear that quickly gets to an impressive size. It is not hardy in the UK and needs to be overwintered indoors in a large container. This combination of being frost-tender and its large size makes it a challenging cactus to cultivate in the UK. It will usually only suit those with enough indoor space to keep it alive over the winter. In warmer areas it can be over-wintered in an unheated glasshouse but it should always be covered in several layers of heavy-grade fleece. If you are lucky enough to be able to meet its rather exacting cultivation requirements you will be able to enjoy a magnificent plant. Its cladodes are some of the largest in the Opuntioideae and really do grow as large - if not larger - than dinner plates, from where it gets one of its many common names. They are a striking blue-grey in colour with long white spines and rufous glochids.

Opuntia robusta can be watered generously during the summer as long as it has a very free-draining gritty mix. It should be kept completely dry from mid-October through to late February/early March with just small amounts of water given to break its dormancy, gradually increasing the amount and frequency of the waterings into the summer.

I did once overwinter a large Opuntia robusta outdoors in Greater London. It was a mild winter and it survived. The following year I grew complacent and left it out. It turned to mush. My advice is, don't be tempted to try this species outdoors...you will lose a very beautiful plant.